JPS6118189B2 - - Google Patents

Description

Detailed Description of the Invention The present invention is an insulating liquid removal method that uses corona discharge to remove excess insulating liquid adhering to a transfer photoreceptor, transfer material, photosensitive sheet, etc. in the copying process of various electrophotographs. It is related to the device. More specifically, the present invention develops an electrostatic latent image formed on the surface of a transfer photoreceptor with a liquid, and then removes any excess liquid developer that adheres to the transfer photoreceptor before transferring it to a transfer material, and removes any excess liquid developer that adheres to the transfer photoreceptor before transferring it to a transfer material. Excess liquid developer adhering to the transfer material,
Alternatively, the present invention relates to an insulating liquid removing device that removes excess liquid developer adhering to the surface of a photosensitive sheet after developing an electrostatic latent image formed on the surface of a photosensitive sheet with a liquid and before fixing the image.

In a transfer type wet type electrophotographic copying apparatus, an electrostatic latent image on the surface of a photoreceptor is generally developed with a liquid developer, the developed image is transferred to a transfer material, and the transferred image on the transfer material is fixed. On the other hand, the photoreceptor is cleaned with a cleaning liquid in a cleaning device to remove residual developer remaining on the photoreceptor after transfer, and the cleaned photoreceptor is reused. In such a conventional electrophotographic process, the copied image on the transfer material has fogging even in bright areas of the original image, and also has image deletion, making it extremely unclear and difficult to see. This is because when the electrostatic latent image on the surface of the photoconductor is developed, excess developer is attached to the surface, and the developer usually contains at least toner and carrier, and the internal image area of this toner. In addition, floating toner is fixed as it is, and in the transfer method, toner is transferred and adhered to the non-image area during transfer, and toner that is attracted to the image area is removed from the image by the pressure during transfer, etc. It is thought that this is due to the negative effects of water leakage. On the other hand, since a considerable amount of excess carrier is attached to the developer transferred onto the transfer material, the carrier liquid is greatly consumed and the frequency of replenishment increases. For this reason, conventionally, after development, a squeezing roller or the like is arranged on the photoreceptor to squeeze out the excess developer. However, it is inevitable that the use of this squeezing roller will cause image disturbances, similar to the transfer process described above, and the use of a squeezing roller to remove excess developer on the transfer material will also cause similar image disturbances. It was inconvenient.

In addition, after liquid development of the electrostatic latent image on the surface of the photosensitive sheet,
If the excess developer on the photosensitive sheet is removed with a squeezing roller, it is inevitable that image disturbances will occur, and if heat drying is performed without squeezing at all, carrier gas will be generated due to this, which is extremely hygienic as mentioned above. It was spot on.

In order to solve the above-mentioned problems, an improved insulating liquid removal device has been proposed and implemented, which applies corona discharge to the excess insulating liquid adhered to the surface of the holding member in conventional electrophotographic copying machines to squeeze out the liquid. ing.

That is, in an electrophotographic copying apparatus, a transfer photoreceptor or a photosensitive sheet has excess developer attached to it after liquid development is completed, and a transfer photoreceptor or photosensitive sheet has excess developer attached to it after completion of transfer of a liquid developed image. A corona discharge of arbitrary polarity is applied from the surface of a holding member to which an insulating liquid such as a transfer material is attached, thereby removing the insulating liquid. That is, by moving the corona discharger relative to the surface of the insulating liquid and sequentially charging it from one side to the other, the liquid surface becomes depressed and a squeezing effect appears and is removed. As a result, the remaining liquid is almost completely pushed out and removed.

The insulating liquid squeezed out as described above is then removed by liquid removal means such as suction or gravity.

In the case where the insulating liquid on the holding member is squeezed and removed by corona discharge, the discharge polarity will be described. First, when the target subject to the aperture action by corona discharge is a developer that has developed an electrostatic latent image on the surface of a photoreceptor, the process is as follows. The charging polarity due to corona discharge is preferably the same as the polarity of the toner used to develop the electrostatic latent image on the surface of the photoreceptor. That is, since the developer is squeezed while the developer toner is pressed against the surface of the photoreceptor by the electric charges generated by corona discharge, the squeezing effect can be obtained without disturbing the image. However, if the electrostatic latent image on the surface of the photoreceptor strongly attracts toner, charging polarity by corona discharge for developing and removing the image can be carried out satisfactorily without disturbing the image in any way even if the polarity is opposite to that of the developed toner. be. Therefore, although some selection of conditions may be required, it can be said that good effects can be obtained with either polarity. Next, when squeezing and removing an insulating liquid such as a cleaning liquid, the corona discharge polarity can be selected quite freely. The above is not limited to applying direct current to corona discharge, but if the surface of the insulating liquid can be charged by applying alternating current voltage, sufficient aperture removal effect has been obtained in experiments, so alternating current voltage application is also applicable. be.

In order to more efficiently remove the insulating liquid on the holding member by corona discharge as described above, it is necessary to add some means to the ordinary corona discharger. Possible methods for this include increasing the voltage applied to the corona discharge electrode or bringing the corona discharge wire closer to the holding member. However, these methods inevitably cause the photoreceptor to be strongly charged, causing undesirable conditions such as spark discharge and dielectric breakdown of the photoreceptor. Therefore, the squeezing effect of the insulating liquid is performed without opening the discharge potential. That is what is desired.

On the other hand, in order to solve this problem, a corona discharger has been proposed in which only an insulating member is provided near the discharge opening as shown in FIG. That is, in FIG. 1, 1 is a conductive shield for a corona discharge electrode 2, 3 is an insulating member, and 4 is a holding member having an insulating liquid 5 on its surface. According to this configuration, when the insulating liquid on the holding member is squeezed and removed by corona discharge, the surface of the insulating member facing the corona discharge electrode side is charged with an electric charge. This amount of electric charge is generated between the surface of the insulating member facing the corona discharge electrode and the electrode located on the opposite surface side, which can induce charges of opposite polarity to the charge accumulated on the surface facing the corona discharge electrode. The capacitance is determined according to the capacitance of the capacitor formed by the member (for example, a photoreceptor) that functions as a Therefore, the amount of electrical charge differs locally depending on the rubber, surface properties, etc., and this causes uneven corona discharge to the holding member and causes local unevenness in the squeezing effect.

The present invention attempts to solve this drawback.

The purpose of the present invention is to provide an improved insulating material that can be used in an electrophotographic copying device to more efficiently squeeze out excess insulating liquid on the surface of a photoconductor without increasing the charging potential when removing it by corona discharge. An object of the present invention is to provide a liquid removal device.

Another object of the present invention is to provide an insulating member at the discharge opening of a corona discharger so that the corona discharge electrode faces the surface of the corona discharge electrode when removing insulating liquid excessively adhered to the surface of a photoreceptor in an electrophotographic copying apparatus by corona discharge. To provide an improved insulating liquid removing device which is provided with conductive members on the opposite side and the opposite side, thereby narrowing the corona discharge width and strongly discharging the corona discharge to that part, thereby improving the squeezing removal effect of the insulating liquid. It is in.

That is, as a result of research on the removal of the insulating liquid on the holding member, it was found that it is necessary to apply corona discharge rapidly in order to obtain a high squeezing effect. In other words, even if the charging potential of the insulating liquid becomes high after applying a corona discharge, in other words, even if the charging is done strongly, if the charging is done gradually over a wide range, the squeezing effect of the liquid will be extremely weak. be. On the other hand, even if the discharge potential is low, if corona discharge occurs rapidly in a narrow range, the throttling effect becomes very large. In the present invention, in order to perform this corona discharge rapidly in a narrow range, an insulating member is provided near the discharge opening of the corona discharger, and a conductive member is provided on the surface facing the corona discharge electrode and the opposite surface. Even if the discharge potential is lowered, the amount of charge from the corona discharge electrode to the holding member due to the charge on this capacitor is much larger and narrower than when the member is not provided near the corona discharge opening. The squeezing removal effect of the insulating liquid became remarkable.

The insulating liquid removal device of the present invention will be specifically described below with reference to the drawings.

First, the insulating liquid removal device of the present invention will be explained with reference to FIG. 2. In the figure, 1 is a corona discharge electrode;
2 is a grounding shield member having a discharge opening; 3
₁ , 3 _{, and 2} are corona discharge convergence members disposed in the discharge openings of the shield member. The discharge wire 1
high voltage is applied by the power cord. Reference numeral 4 denotes a holding member for the photoreceptor, transfer material, photosensitive sheet, etc., which moves in the direction of the arrow. Reference numeral 5 denotes an insulating liquid such as a developer, and the discharge opening of the insulating liquid removing device is arranged to face the holding member. In this insulating liquid removal device, the discharge width from the corona discharge electrode onto the holding member is narrowly limited by the converging member 3. The insulating liquid 5 on the holding member 4 is charged by this corona discharge, and charges of the same polarity are repelled from each other by this charging, or the liquid is depressed and squeezed out by the electric field of the charges charged in the insulating liquid. It seems likely that A dielectric material is used as the focusing member 3, and a conductive member such as metal is provided on the side facing the corona discharge electrode and the opposite side of the dielectric material, and the conductive member provided on the opposite side is grounded. applicable. (A voltage may be applied instead of grounding.) As a result, the present invention suppresses the charging potential on the surface of the insulating liquid on the holding member 4 due to corona discharge to a low level, and improves the squeezing removal effect of the insulating liquid 5. It was designed so that Since a conductive member is provided as the convergence member 3 on the side of the insulating member facing the corona discharge electrode, charging by the charge from the corona discharge electrode becomes uniform, and no unevenness occurs in corona discharge. Furthermore, since the insulating member is narrowed and the conductive member serving as the opposing electrode of the capacitor is arranged, the distance between the two conductive members is narrow, and therefore the capacitance of the capacitor formed by this is different from the front and back as described above. Since the capacitance is larger than that of a capacitor formed only by placing an insulating material without a conductive material in the capacitor, fluctuations in the amount of charge due to repeated corona discharges and stops can be averaged out, and the aperture effect is stable. That's what you get.

Specific examples will be described below with reference to the drawings.

In the embodiment shown in FIG. 2a, _the first corona discharge convergence member ₃₁ , which has a large influence on the internal liquid squeezing effect of the first corona discharge convergence member ₃₁ , and the insulating member ₆₁ and its A conductive member ₇₁ is provided on the side facing the corona discharge electrode, and a conductive member ₇₂ is provided on the opposite side, and the conductive member ₇₂ on the opposite side is grounded to form a capacitor. With this configuration, the capacitor capacity of the first corona convergence member ₃₁ is increased, and since the side facing the corona discharge electrode is made conductive, uneven charging is avoided, and the member maintains an even corona discharge current. Since it can be applied rapidly to the surface, the squeezing effect is effectively achieved.

In the embodiment shown in FIG. 2b, both the first and second corona discharge convergence members 3 ₁ and 3 ₂ are
₁ , 6 ₂ , conductive members 7 ₁ , 7 ₂ provided on the side facing the corona discharge electrode, and conductive members 8 ₁ , 8 ₂ provided on the opposite side. The magnetic member is grounded to form a capacitor. This configuration provides a better aperture effect than the configuration shown in FIG. 1a.

In the embodiment shown in FIG _. 2c, the configuration of the corona discharge focusing member is exactly the same as that shown in _FIG . The provided conductive member 7 ₂ ,
A voltage is applied to 8 ₂ , thereby determining the charge voltage charged to the conductive members 7 ₁ and 8 ₁ on the side facing the corona discharge electrode. It is also possible to adjust and control the amount of corona discharge current by making this voltage application variable and controlling the charging voltage.

As described in detail above, the insulating liquid removal device of the present invention includes an insulating member as a corona discharge focusing member and a conductive member on the side opposite to the side facing the corona discharge electrode. Since the reference voltage of 1 is applied, it is possible to adjust the aperture strength on the surface of the insulating liquid and adjust the charging potential on the surface of the photoreceptor. Therefore, for example, when applying an electrostatic latent image on a photoreceptor to a liquid electrophotographic copying device to squeeze out excess developer before transfer, it is necessary to take into account the situation in order to obtain a high-quality printed image. It is necessary to adjust the aperture strength as shown below by adjusting the voltage applied to the focusing member accordingly. When the speed of the photoreceptor drum is variable... Change the transfer paper to perform more powerful aperture at a faster rate... Oil absorption Changes in developer temperature that cause more powerful aperture to be performed as the temperature deteriorates... Changes in the image that cause more forceful aperture to occur as the temperature decreases... Stronger aperture can be applied to line images compared to solid black images.

As described in detail above, in the insulating liquid squeezing device of the present invention, by adjusting the movement of the converging members 3 ₁ , 3 ₂ , it is possible to obtain a liquid squeezing effect depending on the spot, and it is possible to adjust the charging potential to the holding member. This is extremely effective as it can improve the effect of removing the aperture.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the structure of an insulating liquid squeezing device, and FIGS. 2a, b, and c are illustrations of an embodiment of the insulating liquid removing device of the present invention. In the figure, 1 is a corona discharge electrode, 2 is a shield member, 3 ₁ , 3 ₂ is a focusing member, and 4 is a holding member.

Claims (1)

[Scope of Claims] 1: a corona discharge electrode; a shield member that surrounds the corona discharge electrode, is electrically insulated from the corona discharge electrode, and has a discharge opening facing the surface of a holding member that holds an insulating liquid; first and second corona discharge convergence members provided near the opening, the first and second corona discharge convergence members being spaced apart from each other so that the corona discharge from the corona discharge electrode passes between them; a corona discharge convergence member, and the first corona discharge convergence member includes an insulating member, a conductive member provided on the corona discharge electrode side of the insulating member, and the holding member of the insulating member. a conductive member provided on the member side and to which a voltage (including ground voltage) is applied, and the second corona discharge convergence member is an insulating member, or an insulating member; a conductive member provided on the corona discharge electrode side of the insulating member;
a conductive member provided on the holding member side of the insulating member and to which a voltage (including ground voltage) is applied;
An insulating liquid removal device characterized in that an insulating liquid removal device is characterized in that an excess liquid is removed by applying a corona discharge that has passed between the corona discharge convergence members.